Function readSessionStartDate

src/utils/stats.ts:994–1036

(
  filePath: string,
)

 * head (caller falls through to the full read — safe default).
 */
export async function readSessionStartDate(
  filePath: string,
): Promise<string | null> {
  try {
    const fd = await open(filePath, 'r')
    try {
      const buf = Buffer.allocUnsafe(4096)
      const { bytesRead } = await fd.read(buf, 0, buf.length, 0)
      if (bytesRead === 0) return null
      const head = buf.toString('utf8', 0, bytesRead)

      // Only trust complete lines — the 4KB boundary may bisect a JSON entry.
      const lastNewline = head.lastIndexOf('\n')
      if (lastNewline < 0) return null

      for (const line of head.slice(0, lastNewline).split('\n')) {
        if (!line) continue
        let entry: {
          type?: unknown
          timestamp?: unknown
          isSidechain?: unknown
        }
        try {
          entry = jsonParse(line)
        } catch {
          continue
        }
        if (typeof entry.type !== 'string') continue
        if (!TRANSCRIPT_MESSAGE_TYPES.has(entry.type)) continue
        if (entry.isSidechain === true) continue
        if (typeof entry.timestamp !== 'string') return null
        const date = new Date(entry.timestamp)
        if (Number.isNaN(date.getTime())) return null
        return toDateString(date)
      }
      return null
    } finally {
      await fd.close()
    }
  } catch {
    return null
  }
}

function getEmptyStats(): ClaudeCodeStats {
  return {